Electrical devices need to be connected to an electrical power source in order to be operated. Unless the electrical device carries an internal power supply such as a battery, the device is dependant upon significant infrastructure to provide it with power. The power providing infrastructure typically includes a power outlet wired to a mains power line. Power cables connected to electrical devices typically draw power from a mains line via plug-and-socket connectors.
In recent times, there has been a rapid proliferation of electrical devices in both the home and work environments. In a modern kitchen for example, there is need to provide electricity to numerous high power appliances such as ovens, refrigerators, dishwashers, washing machines and dryers, as well as to various worktop gadgets such as toasters, kettles, mixers and the like which are increasingly considered necessities rather than luxury items. The high power devices are usually stationary, hard-wired to high current mains outlets, whereas gadgets are often movable, being stored away in cupboards and brought out to the worktop when necessary.
The infrastructure required to provide power to these devices has not always been able to keep up with the increased demand for power. In many kitchens, such devices often need to share a single power outlet. In order to connect many electrical devices to the mains, power strips may be used. Power strips, provide many sockets all of which connect to the mains via a single plug-and-socket connector.
Although convenient, power strips can represent a significant hazard. A single plug-and-socket connector is usually designed to provide power to a single appliance. By plugging in a number of appliances to a single connector, the connector may become overloaded which can cause overheating or even fire. This is a particular problem where devices are regularly plugged and unplugged into the socket. Disconnecting an electrical load from a power source by unplugging a plug-and-socket connector can produce sparking which damages the connectors and may cause them to heat up excessively. Some small gadgets, such as kettles, which require unplugging to be filled, nevertheless require high currents. Especially in the kitchen environment, the greater the number of power sockets, the greater the chance that water may spill into them. It has been proposed that inductive rather than conductive power connectors may be used to reduce this hazard.
Inductive power coupling allows energy to be transferred from a power supply to an electric load without any conduction path therebetween. An inductive coil and a driver are wired to a power supply. The driver applies an oscillating electric potential across the inductive coil which serves as the primary coil of an inductive couple. The oscillating electric potential induces an oscillating magnetic field which may induce an oscillating electrical current in a secondary coil placed close to the primary coil. In this way, electrical energy is transmitted from the primary coil to the secondary coil by electromagnetic induction without the two coils being conductively connected. An electric load wired in series with the secondary coil may draw energy from the power source when the secondary coil is inductively coupled to the primary coil.
Because there is no conductive path between the connectors, inductive power connectors do not spark. Furthermore because electrical components of inductive power outlets may be sealed to prevent water from penetrating the connection, they are safer in wet environments. Nevertheless, inductive power outlets require additional infrastructure, such as drivers and inductive coils, which are not generally available with existing mains power lines.
There is a need for inductive power outlets which can be integrated with existing mains power lines without the need for additional infrastructure. The present invention addresses this need.